1. Field of the Invention
The present invention relates to an apparatus or the like which autonomously moves along a target path.
2. Description of the Related Art
As robots have become more sophisticated in functionality, there are increasing opportunities for the robots to perform jobs or works such as carrying luggage or guiding human beings to their destinations, and the need for the robots to move while preventing contact with the human beings is increasing. In this relation, a technique to issue a sign from a robot which can be visually or auditorily recognized by the human beings surrounding the robot to thereby inform them of the traveling direction of the robot has been proposed (see Japanese Patent Application Laid-Open No. 2006-035381). Further, a technique to retrieve a path within a range of path selection filter for preventing a robot from contacting an obstacle and, if there is no path within the range, to enlarge the range of the path selection filter in a stepwise manner to retrieve a new path, has been proposed (see Japanese Patent Application Laid-Open No. 2006-236098).
If the human beings surrounding the robot do not know the meanings of the signs issued from the robot, however, the behavior of the robot predicted by the human beings may differ from the actual behavior of the robot, thereby rather confusing the human beings. Further, if the change of the traveling direction of the robot is small, it will be difficult to cause the human beings surrounding the robot to expect that the robot will change the traveling direction. When a person moves his/her position based on false prediction or estimation, the possibility of contacting the robot may rather increase. In such a case, it will be difficult for the robot and the human beings surrounding it to move in a cooperative manner.